Răspuns :
X-NR NECUNOSCUT
(X+217):100=B+1980=2000/-1980
B=20
(X+217):100=20/×100
X+217=2000/-217
X=1783
(X+217):100=B+1980=2000/-1980
B=20
(X+217):100=20/×100
X+217=2000/-217
X=1783
( a + 217) : 100 + 1 980 = 2 000
( a + 217) : 100 = 2 000 - 1 980
( a + 217) : 100 = 20
a + 217 = 20 × 100
a + 217 = 2 000
a = 2 000 - 217
a = 1 783 → numarul
( a + 217) : 100 = 2 000 - 1 980
( a + 217) : 100 = 20
a + 217 = 20 × 100
a + 217 = 2 000
a = 2 000 - 217
a = 1 783 → numarul